Devices of this type are known in the state of the art and are used in different applications, such as for example the steering assistance of high-power engines or in making variable distance adjustments of parts relatively moving between each other.
Currently, this type of devices comprises a locking actuator consisting of a hydraulic cylinder with a chamber in which a piston is slidingly connected on a side or on two sides to at least one piston rod which can be translated axially together with the movement of the piston along the cylinder, the cylinder being provided with two inlet ports which respectively communicate with one of the two chambers of the cylinder separated from each other by the piston and the two ports being connected to a bypass duct in which a preventing unit to prevent the fluid flow, which can be controlled in the active or inactive preventive condition, typically a valve, preferably a servo-controlled valve, is provided.
Thanks to a partially closed condition of the valve, the preventing of the fluid flow or the reduction of the flow port allows to completely close the fluid flow from a cylinder chamber to the other and to increase the flow resistance and therefore to stop the displacement of the piston in the cylinder or to brake such displacement.
By acting on a switching unit, the user can therefore control the switching condition of the preventing unit between the active and inactive conditions and therefore lock, brake or free the actuation of a kinematic control chain of a control system.
The locking member can be operationally coupled to any element of a kinematic control chain and is therefore extremely versatile. The use of preventing units that can be activated and deactivated by electric or electromechanical or electronic control makes it extremely easy to achieve and implement the switching unit of the locking actuator.
Despite the locking devices of this type have optimal functionalities, they have the drawback of requiring preventing units, such as valves of relatively complex construction, providing movable mechanical parts and being subject to wear as far as the sealing in a closed condition is concerned. Moreover, there also being a need for braking the kinematic chain, the control of the valves must operate progressively, requiring for example the need of actuations with electric motors rather than with electromagnets.
This involves integration issues for the locking devices both in newly constructed systems and when modifying existing systems.